SCORE!
My friend gave me a barrel today that has no liner!!! the inside is shiny and clean! It has a closed top...it appears to me that if I were to go around the outside edge of the seem or roll where the lid and the drum meet that the lid could then still be used and would "seat" down into the barrel for a good tight seal. OR, should I just cut the top out from inside the lip leaving the "roll" OR cut the top off just below the roll then grind it smooth? comments?

I will take some pics tomorrow...

SCORE #2
My same friend has a 5' piece of heavy 2 inch ID pipe with a 1 1/2 inch commercial ball valve on one end...he gave me that also! Will that be enough for the air intake or should I plan on a second (and even third?) air intake?

When i did mine, i cut the top out and used a lid from another drum temporarily until I bought a cheap kettle from Wally Mart and used it's lid.
I think it would be difficult at best to remove the rolled-on lid. The dome lid is the way to go anyhow, IMHO...

dome lid definatly the way to go. pit 4 brains lid with the hindges looks good. i got lucky and found a old char broiler grill for $5. so no hinges for me. also if you decide to cut the top out lots of us use this piese for a ash pan just fold up the edges. just a idea when i cut mine out i used a saw zaw and let the guid on the saw zaw ride the inside of the lip. makes a perfect circle. then i cut a 2 inch gap in the new lip on both sides to allow my bottom grate to slide threw. works perfect my first smoker and i love it so far.

use an angle grinder and grind around the outside of the lip just until you can see the seam where the lid fits over the drum. Then use a chisel to pop the lid off. Works great, and you end up with a tight-fitting lid.

After building one UDS out of an open-head drum, and two out of closed drums, I'll use a closed-head drum every time in the future. As a bonus, with the closed-head units, they are less likely to be out of round...